Impact of Dietary Zinc Chloride Hydroxide and Zinc Methionine on the Faecal Microbiota of Healthy Adult Horses and Ponies.

The research article studies the effect of different zinc supplements, specifically zinc chloride hydroxide and zinc methionine, on the gut microbiota of healthy horses and ponies. It suggests that high levels of dietary zinc could harm the richness and activity of the intestinal microbiota, raising concerns for animal gut health.

Methodology

• The study encompassed a total of eight healthy adult ponies and two healthy adult horses. They were subjected to different dietary zinc concentrations achieved with the help of two types of zinc supplements – zinc chloride hydroxide and zinc methionine.
• They were treated with zinc for six periods, each of 4 weeks, making a total 24 weeks of observation.
• Faecal samples were collected from the horses at the end of each treatment period. These samples were then subjected to analysis of microbiota via 16S rDNA sequencing methods and microbial metabolites.

Results

• The results showed that as dietary zinc concentrations increased, a decrease in the richness of the faecal microbiota was observed. This occurred regardless of which zinc compound was used.
• Furthermore, an abundance of Bacteroidetes and Fibrobacteres microorganisms and metabolites like acetate and total short-chain fatty acids in the animal faeces was seen to decrease with high zinc intakes.
• Effects at the bacterial order, family, and genus level were also detected. These differed based on the type of zinc compound used, with more pronounced effects seen for zinc chloride hydroxide.

Conclusions

• The study concluded that high dietary zinc levels could decrease the richness and fermentative activity of the faecal microbiota in horses. Even though all the animals remained healthy throughout the study, the results suggest potential implications for gut health.
• Notably, the study also observed that the effects varied between the two different zinc compounds, pointing towards differences in the bioavailability of organic and inorganic zinc sources in horses and ponies.
• The research points at the need for more studies concerning the effects of dietary zinc on gut health, and the distinction between the use of different zinc compounds in equine nutrition.